Muitiofeice telephone system



Dec. 30, 1924.

J. WICKS MULTIOFFIGE TELEPHONE SYSTEM Fied JCn. 20, 1922 8 Sheets-Sheet l SIL 1 M :J4 MH EN HM q B In-mmf- Jahn Maks Z. fn-y.-

Dec. 30, 1924.

l J, IWICKS MULTIOFFICE TELEPHONE SYSTEM f Filed Jan. 20, 1922 8 Sheets-Sheet 2 TLUEI'L DF Jjhn M1 Inks .ETT-J Dec 30, 1924.

1,520,990 J. wlcKs MULTIOFFICE TELEPHONE SYSTEM Filed Jan. 20, 1922 8 Sheets-Sheet 3 Jnhn H'Lcks Dec. 30, 1924.

J. WICKS MULTIOFFICE TELEPHONE SYSTEM Filed Jan. 20, 1922 8 Sheets-Sheet 4` Jal-m Inl-mk? 4% Z. 255W- Dec. 3o, i924.

J. WICKS MULTI OFFI CE TELEPHONE SYSTEM Filed Jan. 20, 192,2, 8 Sheets-Sheet 5 J. WICKS MULVTIOFFICE TELEPHONE SYSTEM Dec: 3o, 1924.

Filed'Jan. 20, 192.2. 8 sheets-sheet 6 Imran :1r

Jahn Maks Dec. 30, l 924.

J. WlcKs MULTIOFFICE TELEPHONE SYSTEM Filed Jan. 20, 192.2 8 Sheets-Sheet '7 Dec. 30, 1924. 1,520,990

\ J. WICKS MULTIOFFIGE TELEPHONE SYSTEM Filed'Jan. 20, 1922 8 Sheets-Sheet 8 Imfen' ZEI" Jul-m Hicks .5% Z- .H-r

Patented Dec. 30, 1924.

UNITED STATES nazaten PATENT oFFicE.

JOHN WICKS, OF CHICAGO, ILLINOIS, ASSIGNOR TO AUTOll/IAJO ELECTRC COMPANY, OF CHICAGO, ILLINOS, A CORPORATON UFF XLLINOIS.

MULTIOFFICE TELEPHQNE SYSTEM.

Application filed January 2G, 1922.

To all rollout it may concern.'

Be it known that l, donn lVions, a citizen et the United States ot America, and a resident ci" Chicago, Cook County, and State 5 ot Illinois, have invented certain new and useful Improvements in Multioiiice Telephone Systems, of which the following is a spccilication.

lhe present invention relates to multiotlilce telephone systems in general, but is concerned more particularly with such sysw tems as comprise both manual and automatic oiiiees, and the object ot the invention, broadly stated, is the provision of new and .improved arrangements :tor handling calls which originate at a manual oilice and which are intended for subscribers of automatic oi'iices.

The invention is particularly applicable to niulti-ollice. systems that are being` changed, an ollice at a time, according to common practice, from manual to automatic operation. In order to etllect such a change, the A operators, in each oit the manual offices that are to remain manual tor the time being, are provided with the necessary equipment fory extending` calls to cach ot the automatic o'llnices. lt is, thereiliore, an object oft the invention to provide 30 the A operators with el'licient and easily manipulated apparatus for extending` calls to automatic oilices. It is a 'further object to provide a few senders which are common to a ,great many operators. '.lhere are varions other objects not specifically mc1i tiolied now, all oit which will be pointed out and lully explained hereinafter, with reterence to the accompanying drawings.

llor an understanding; of the circuits, Figs. l, El, and 3 ot the drawings should bc laid out in order with the corresponding lines at the ends thereof in alignment: Figs. 4i and 5 should be placed in order vwith the corresponding' lines at the ends thereof in alignment and with the conductors on Fig. 5, that areturned up, in alignment with the correspondingv conductors on Fig, 2 that are turned down; and Figs, 4G, 7, and 8 should be placed in order with the corresponding lines at the ends thereof in alignment, with Fig. 7 directly under Fig. il, and with the corresponding inter-connecting` lines between the two iigures in alignment. When thus arranged, the drawings show suliicient equipment 'for a complete connection from a Serial No. 53G,52.

calling` manual substation A, Fig. l, to a called automatic substation A', Fig'. 8, together with the necessary equipment at the A operator-s position for controlling' the automatic switches. llt will be noted that vthe connection, when established, includes the calling` substation A and associated line, the cord circuit U, an outgoing trunk passing through the trunk equipment T, a secondary distributing` switch C, automatic repeater E, selector D, connector H, line switch C', and the called automatic substation il and associated line. rlhe apparatus shown in the remaining figures is not included in the talking,` connection and is used merely to control the automatic switches.

The equipment shown in Fig. l, compris- ,ing the substation il, the associated line and jacks, and the operators cord circuit C), is standard manual equipment such as is in common use; The trunk on the right-hand side ot Fig. l, which terminates in the jacks J2 and J3, is provided with an indicating lamp at each oit the jacks Yfor a purpose to be hereinafter explained.

The trunk relays T, Fig. 2, are used as a yineans tor switching` the trunk troni the con- Athe reverse battery supervision of the automatic switches into high resistance supervision tor the iiianual equipment.

The selector D, 3, `is an automatic selector switch olf the well known vertical and rotary type in which thebank contacts are arranged in horizontal rows or levels. The circuits and functions ot this switch are well known and accordingly do not need to be described herein.

The connector H is mechanically the saine as the selector D. Most of the circuits of this connector have been omitted ior the sake ot simplicity, only the line release and hack bridge relays beine; shown.

The line switch C is a rotary line switch l (lll ot the well known type in which the wipers have no normal position land move in a forward direction only.

The called substation A is an automa-tic substation of the well known type, having the usual, talking, signalling, and switch controlling instrumentalities.

A detailed description of automatic switches such las are referred to above con1 prising the selector D, connector H, and the line switch C, may be found in Automatic Telephony which is a book by Smith and Campbell and is published by iIcGraw-'Hill Book Company, New York, N. Y.

The trunk selector TS, Fig. 5, is mechanically7 identical with the rotary line switch C, Fig. 8, just described. The circuits of this switch, however, have been altered to meet the di'tlerent requirements under which it must operate. The trunk selecting switch TS is identical with the trunk selecting switch TS. The switch TS is assumed to have access to trunks leading to automatic ottice No. 1, and the switch TS is assumed to have access to trunks leading` to automatic ofice No. 2.

The sender selector SS, associated with the trunk selectors TS and TS, is mechanically identical with either ot the latter with the exception that, since the number of wipers carried by this switch is larger than can be conveniently mounted on the particular mechanical embodiment ot the switch used, the wipers have been arbitrarily divided into two parts, one part being mounted on one switch frame, and the other part being mounted on an adjacent switch trame. The two operating magnets 263 and 264i are operated synchronously in a manner to be explained fully hereinafter.

Of the operators calling push buttons shown in the upper left-hand corner ot' Fig. 5, the first two, 221 and 222, are used to select either of the two switches TS or TS. The next ten buttons, comprising buttons 20l-210, inclusive, are used by the operator in setting up the digits of the number after the desired ollice has been selected by operating either ot the buttons 221 or 222. The last push button 215 is a release push button and is used to release a partly set up number before it is sent out, in case the operator discovers that she has made a mistake and pushed the wrong button.

The translating and controlled relays, Fig. 4, are used primarily to permit va reduction in the number oit' wipers carried by the sender selector SS? The 'functions ot these relays will become more apparent upon a 'further perusal of the speciiication.

The counting switch CS, Fig. 6, is inechanically identical with any ot' the other rotary switches shown, such as the switches TS and TS, Fig. The 'function of this switch is to count the impulses, as they are being sent, and to switch over to the next digit when a sutlicient number of impulses have been sent in any one digit.

Fig. 7 shows the storage relays for storing up the second digit, as the number is being set up by the operator. Fig. 8 shows duplicate equipment for storing up the third digit. It will be understood that the storage sets for storing up each or' the remaining digits are exact duplicates of Fig. 8.

The apparatus, having been described more or less in general, will now be described in connection with a detailed description of its operation. For this purpose it will be assumed that the subscriber at substation A desires to converse with the subscriber at substation A whose line terminates in automatic office No. 1 and whose number will be assumed to be 1456. Vhen the receiver is removed yat substation A, a circuit is closed over line conductors 2 and 3 for line relay 6. Line relay 6, upon energizing closes a circuit for the lamp L. The operator, upon observing the lighted condition of lamp L, inserts an answering plug of an idle cord circuit into the jack J, the plug P of the cord circuit O, i'or example, thereby closing the circuit for cut oit relay 5 in series with supervisory lamp L. Cut off relay 5, upon energizing, disconnects the line conductors 2 and 3 from ground and from line relay 6, respectively, whereupon the said line relay 6 becomes deenergized and the lamp L becomes extinguished. Supervisory relay 7 in the cord circuit O, upon energizing over the calling line, places a shunt around the supervisory lamp L so as to prevent the said lamp from becoming lighted at this time.

The operator now throws her key K, which is a combined listening and ringing key, into listening position, thereby connecting up her head set so as to enable her to converse with the calling subscriber. The calling subscriber now tells the operator with which subscriber he desires to be con* nected, and upon learniifig that it is the subscriber at substation A in the automatic oitice No. 1, the operator restores the key K to normal, and operates the ottice select.- ing push button 221, Fig. 5, which button corresponds to the lirst digit 1 ot the desired number. Upon being operated, push button 221 closes the following circuit: from ground by way of said push button 221, conductor 226, armature 2411 and its resting Contact, and the upper winding` ot relay 280 otl the trunk selecting switch TS to battery. Relay 280, upon energizing, prepa-res a circuit for switching relay 251 at armature 288; and at armature 283 closes the following circuit: from ground by way of the normally closed contacts controlled by armature 27T oiI relay 269, armature 283 and its working Contact, switching relay 268,

armatures 265 and 266 and their resting,l contacts, and stepping relay 267 to battery. jrs a still i'urther result or the energization ot .1 280, it connects test wiper 350 of the sender selector SS to a point in the circuit between switching relay 268 and stepping relay 267, at armature 281i. Assuming that the wipers of the switch SS are stand-ing upon a busy sender, switching relay 268 is short circuited and stemmig relay 267, upon energizing, closes a locking circuit for itsel't at armature 270, and at armature 271 and 272 closes the circuits et stepping magnets 268 and 261. U pon energizing, each oit the said magnets attracts its arn'iature so as to cause the associated pawl to engage the neat notch on the wiper driving' ratchet wheel. llpon looth magnets completing; their strolrc, the circuit olf stepping' rela;Y 267 is opened at armatures 265 and 266, and the said relay 267, upon deenergizing, opens the circuits ot the n' `e'nets 263 and 261, whereupon the said mannets deenergize, thereby driving` the wipers 243-350, inclusive, into engagement with the next set o contacts and connecting, up the stepping relay 267 again at armatures 265 and 266. rllhis alternate operation ot stepping' relay 267 and stepping,T magnets 263 and 2611- continues until the wipers have arrived upon a set ot contacts in which the conductors associated with a idle sender terminate.

`When an idle set oit contacts is rezuhed, which set we shall assume is the one shown in 'the drawings, switchingl relay 268, being no longer short circuited, energizes over its previously traced circuit in series with stepping relay 267. The latter relay, however', does not energize at this tiine owing to the high resistance ot switching' relay 268. Switching` relay upon energizing, opens the test circuit and places ground upon test wiper 350 at arinature 2711;, thereby inalring the seized sender busy immediately. As a further result oit the ei'iergrization ot suf'itchrelay 268, it connects up wiper fl-10 at armature 278; places ground upon armature 280 et the trunk selector TS at ar1nature 275; prepares locking;l circuit for relay 280 ot the switch TS at armature 276; and at armatures 258 and 252', connects ground and battery to conductors and 221, respectively. This is done so as to render the operators set up push button set operative.

ln the translating' relays, Fig. 1, the grounding ot conductor 158 by the switch SS, i explained above, closes a circuit for relay 1.08 by way et the nornially closed contacts controlled by armature 106. Relay 108, upon energizing', closes at armature 113 the following circuit: from ground by way oit the working,` contact of armature 113 and said arnniturc, upper winding' ot relay 101;, relays 122, 1241-, 126, and .130 in multiple` relays 121, 1.23, 126, 127 and 120 in multiple,

and the lower winding,l of relay 104, to battery. The relays 121-130, inclusive., are Very still'ly adjusted and consequently none of them energize at this time, and relay 10-1 does not energize at this time because it is diiiierentially wound. As a 'further lresult of the energization ot relay 103, it prepares a locking circuit for itselit at armature 112, and at armature 111 places ground upon conductor 167, thereby closingl the following circuit: from ground, by way ot grounded conductor 167, armature 120 ot' relay 408, Fig'. 6, and its resting contact, normally closed contacts controlled by armature 4123, conductor 424i, resting` contact ot armature 159 and said arniature, relay L153, and relay 1511 to battery. Relays 453 and 154i, upon energizing, connect up conductors 1411-160, inclusive, to relays L1-71-180 inclusive, respectively, at armatures 461-170, inclusive, respectively. The sende1 is now in condition to receive the number as it is set up.

vReturning` now to the switch TS, l? 53, as a. further result of the energization o? relay 28D in response to the operation o push button 221, it closes a circuit tor switching relay 281 and rotary magnet 282 in series, at armature 286; and at armature 287 connects test wiper 3041 to a point bctween said switching relay 281 and said stepping magnet 282. Frein this point the operation depends upon whether the trunk upon which the wipers 301-804, inclusive, are standing, is busy or idle. 1t it is idle, switching relay 281 energizes imn'iediately, but it it is busy there is a ground potential upon the test contact thereof; relay 281 is short circuited; and stepping magnet 282, which interrupts its own circuit, is operated in the manner of a buzzer to advance the switch wipers step by step in search of an idle trunk. i-rssuming` that the trunk to which the conductors 805-308, inclusive extend is the first one found to be idle, switching' relay 281 is no longer short ci: cuited when the switch wipers arrive upofi the contacts in which these conductors terininate and accordingly energize/s. fitepping magnet 282, however, does not energize at this time owing to the high resistance ol' switching` relay 281. Switching relay 281, upon energizing, opens the testing circuit and places direct `ground on test wiper F30-it at armature 202, thereby making the seized trunk busy immediately; connects up wiper 803 to relay 269 at armature 211; and at armature 204 completes the following lock-- ing' circuit for relay 280. Frein ground b f wa 1 or ari'naturs 276 oit rela f 268 and' its working Contact, armature 2941 and iis working contact, armature 285 and its working contact, and the lower winding1 ot relay 280 to battery. As a :further result oit the. enei'gjization ot relay 281, it connects up wiper 301 at armature 280, thereby closing' lli the following circuit for the indicating lamp L4, Fig. 1: from ground by Way of armature 275 and its Working contact of switching relay 268, armature 289 and its Working contact, Wiper 301, the Contact With Which it is in engagement, conductor 305, and indicating lamp L4 to battery. As a still further result of the energization of switching relay 281, it connects up Wiper 302 at armature 290, thereby closing the following circuit: from ground by Way 0f the normally closed contacts controlled by armature 279, armature 290 and its Working contact, Wiper 302, the contact With Which it is in engagement, conductor 306, armature 36 and its resting contact, normally closed contacts controlled by armature 28, armature and its resting contact, and line relay 51 to battery. Line relay 51, upon energizing, closes a circuit for switching relay and stepping magnet 52 in series at armature 58, and at armature 57 connects test Wiper 61 to the magnet The sWitch C noW operates in Well known manner to pick out an idle trunk line, being driven step by step by the buzzer like action of stepping magnet 52, and, upon arriving upon an idle trunk, Which trunk We shall assume is t-he one comprising conductors 63-65, inclusive, does not rotate any further oWing to the absence of ground on test conductor 64. lVhen this occurs, sWitching relay 50, being no longer short circuited, energizes in series With stepping magnet 52. Stepping magnet 52, hoWeyer, does not energize at this time oWing to thel high resistance of switching relay 50. Switching relay 40, upon energizing, opens the set circuit and prepares the holding circuit at armature 54; places a multiple ground upon test conductor 308 at armature 55; and at armatures 53 and 56 disconnects the upper and loWer conductors of the trunk from the. Winding of line relay 51 and ground, respectively, and extends them by Way of Wipers and 62, the contacts With Which the said Wipers are in engagement, and trunk conductors 63 and 65 to the upper and loWer Windings of line relay oftie repeater E. The upper Winding of line relay 7 0 being' connected to battery by Way of the normally closed contacts controlled by armature 80, and resistance 83, line relay 70 energizes over the ground potential coming in over conductor 63, and upon so doing, closes a circuit for release relay 71 at armature 76. Release relay 71, upon energizing, prepares a circuit for relay 7 4 at armature 77 closes a point in the chain of contacts leading te busying conductor 59 at armature 79; and at armature 78 places ground upon conductor 64, thereby establishing the usual holding circuit for switching relay 50 of the sWitch C. This, of course, occurs before the slee7 acting line relay 51 has had time to deenergize. It Will be noted that When ground is placed upon conductor 64, a circuit is closed for the loWer 0r polarizing Winding of the electropolarized relay 72. This Winding alone, hoWever, consisting of few turns of high resistance is not able to energize the relay.

As a result of the energization of line relay 70, it closes a bridge across the conductors of trunk line X as folloWs: from the lower conductor of trunk line X, by Way of impedance 73, upper Winding of electro polarized relay 72, resting contact of armature 82 and said armature, and armature 75 of line relay 70 and its Working Contact. Tn the distant oiiice, the line and release relays of the selector D noW energize in response to the closure of this bridge and prepare the sWitch for operation in the usual manner. Current is noW `floWing through the upper Winding` of electro polarized relay 72, but in a direction opposite to that in Which it is flowing in the loWer Winding and consequently the relay is not energized for the time being. The repeater E is noW ready to repeat impulses to the selector D Which is ready for operation.

Going back noW to the point at Which the circuit for the indicating lamp L4, associated With the jack J2, Fig. 1, Was closed, upon the energization of switching relay 281 of the sWitch TS, as explained, the operator, upon noting the lighted condition of this lamp, releases the office selecting push button 221, Fig. 5, Which she has been holding depressed, and proceeds to set up the remaining digits 4, 5 and 6 of the desired number, the first digit 1 having been taken care of by the depressing of the office push button 221. The operator sets up the second digit 4 by pressing the fourth impulse push button 204, thereby placing battery upon conductor 229, from Whence it extends by Way of armature 239 and its resting contact, conductor 247, Wiper 347, the contact With Which it is in engagement, and conductor 155, to a point betWeen relays 123 and 124. The placing of battery upon conductor 155 shunts relay 123 and practically doubles the current floW through relay 124, Whereupon the said relay 124 energizes and places ground upon conductor 144 at armature 134. As a further result of the decrease of current tloW through relay 123 and the increase of 'current iioW through relay 124, the differentially Wound relay 104 becomes sufliciently unbalanced to attract its armature 114, thereby closing a circuit for relay 102. Relay 102, upon energizing, locks itself to the grounded conductor 158 at armature 109 and at armature 110 prepares a circuit for start relay 101.

As a result of ground being placed upon conductor 144 by relay 124, a 'circuit is closed by Way of the Working contact of CO A some time to describe, requires but a trivial amount of time, inserts the calling plug l2 of the cord circuit O into the proper jack J 2, as indicated by the lighted condition of the lamp Lt. W'hen this occurs, sleeve relay 26 energizes over sleeve conductor 11 in series with supervisory lamp L2 and the said lamp L2 becomes lighted. Sleeve relay 26, upon energizing, closes a circuit for the upper winding of marginally adjusted relay 27 at armature 34e, which circuit includes the resting contact of armature 30 and said armature. The upper winding of relay 27 comprises a small number of turns and has a high resistance, and consequently has only a weak pull at this time. This relay is adjusted so as to pull the armature 37 over against its working contact, but not to operate either armature 36 or armature 38. As a further result of the energization of sleeve relay 26, it prepares a locking circuit for the marginally adjusted relay 25 at armature 33, and at armature connects relay 25 in series with high Wound relay 269 of the switch SS, Fig. 5, by way of the following circuit: from ground by way of relay 269, armature 211 and its working contact, wiper 303 and the contact with which it is in engagement, conductor 807, resting contact of armature 31 and said armature, armature 35 and its working contact, and relay 25 to battery. Relay 269 energizes over this circuit, but relay 25, being marginally adjusted, is not able tc energize on account of the high resistance of relay 269. Relay 269 which not only has a high resistance, but also is efficiently wound, is adjusted very stifl'ly with the exception of armature 27 7 which is given a very weak adjustment. Accordingly, when the circuit of the said relay 269 is closed, armature 277 makes contact with its working contact immediately, but there the movement stops for an interval until the magnetic circuit is built up to a point near its maximum, which requires an appreciable length of time.

Armature 277, upon coming into engagement with its working contact, closes a circuit for start relay 101 as follows: from ground by way of the working contactof armature 277 and said armature, working contact of armature 273 and said armature, conductor 249, wiper 349 and the contact with which it is in engagement, conductor 157, armature 110 and its working contact, and start relay 101 to battery. Start relay 101, which is designed and adjusted so as to energize very quickly and which energizes fully before relay 269 of the switch SS has pulled its armatures all the way up, upon energizing, completes a locking circuit for rela-y 103 at armature 105, disconnects conductor 151 from set up release con' by way of armatures L116 and 4:19, Fig. 6. As a further result of the energization of start relay 101, it connects the grounded conductor 424 with holding conductor 158 and disconnects the latter from the circuit of rela-y 103 at armature 106, thereby furnishing ground to hold up the various relays of the switches SS and TS as will be hereinafter explained. As a still further result of the energization of start relay 101, it connects ground, by way of the grounded conductor 169, with start conductor 168 at armature 107, thereby starting operations in the counting switch CS, Fig. 6, in a manner to be explained fully hereinafter.

Returning now to relay 269 of the switch SS, Fig. 5, the said relay upon finally pulling all the way up, opens the local holding circuit of relay 268 at the normally closed contacts controlled by armature 277, but the said relay 268 remains energized over a circuit which includes holding conductor 158 and armature 2711 and its working contact. It will be remembered of course, that holding conductor 158 was grounded, as explained, by the energization of start relay 110, Fig. e. As a further result of the energization of relay 269, it closes a circuit for push button switching relay 251 at armature 278, the said circuit including the working contact of armature 288 and said armature. Switching relay 251, upon energizing, disconnects conductors 225 and 226 and 228-238, inclusive, from the trunk selecting and sender selecting set shown, and connects them by way of conductors 25a-261, inclusive, to a reserve set, which is an exact duplicate of the one shown, with the one exception that the armature in the reserve set, which corresponds to armature 278 of relay 269, controls a normally closed point in the circuit of relay 251 instead of a normally open point, for a reason which will be explained fully hereinafter. 1n case the operator receives another call at this time, she operates the push buttons in the usual manner and the call is set up on the reserve set, As a still further result of the energization of relay 269, it places a shunt around armature 276 and its working contact at armature 293; and at armature 279 alters the circuit of the upper winding of line relay of the repeater E, so that instead of being grounded by way of the normally closed contacts controlled by a1'- mature 279, the circuit of the said relay e7:- tends as follows: from ground by way of the resting contacts of armatures 4116 and 119 and said armatures, Fig. 6, impulse conductor 165, working contact of armature 108 and said armature, conductor 151, the contact in the bank of the switch SS in which said conductor terminates, wiper 343, conductor 2518, armature 279 and its workto energize and deenergize again.

^ at armature disconnects relay 405 from in multiple with rela)Y 451 and connects it, by way oi conductor 525, in multiple with the cin-responding relay 551 of the third digit storage set, Fig. 8. When this occurs, the circuit ot relay 405 is iinally opened. Relay 405, being slow acting retains its armatures attracted for an interval after which it falls back and connects up impulse relay 407 at armature 415, thereby starting the counting switch Cty' so as to produce the second series of interruptions in the impulse circuit. t will be noted that there is an interval of time, between the sending of the last impulse in the iirst series and the starting of the counting switch GSl for the second series, determined by the length of time required for the slow acting relays 406 and 405 to tall back one after the other. This, it may be stated, is done so as to give the automatic switches time to effect the change over and the trunk hunting operations.

In response to the falling back of relay 405, relay 407 is connected up at armature 415 as before stated, and accordingly beo'ins On the lirst energization of relay 407, stepping magnet 403 is energized and, upon the subsequent deenergization ot relay 407, stepping magnet 403 is deenergized, and wiper 401 is advanced from contact 450 into engagement with a grounded contact, whereupon pickup relay 406 energizes, thereby preparing a locking circuit for stop relay 405 and removing the shunt from around armature 419 and its resting contact. When relay 407 is energized again, the impulse circuit is opened at armature 419, in addition to the closing ot the circuit of stepping magnet 403 at armature 418` and, upon the subsequent dcenei gization of relay 407, the impulse circuit is again closed and stepping magnet 40. upon deeuergizing, advances the wiper 402 into engagement with bank contact 451 with which the first impulse stop conductor 431 is connected. rihis does not produce any effect at this time for the reason that the first impulse stop conductor 431 is not grounded at any point. The operation of 1elay 407 and stepping magnet 403 continues as described until wiper 402 is advanced into engagement with bank Contact 445, at which time the impulse circuit will have been opened iive times.

When wiper 402 comes into engagement with bank contact 445, the -following circuit is closed for stop relay 405: trom ground by way of the third digit stop conductor 542, Fig. 8, working contact of armature 595, fifth impulse stop conductor 485, bank contact 445, Fig. 6, wil er 402, and stop relay 405 to battery. A branch ot this circuit extends by way of conductor 425, armature 455 and its working contact, conductor armature and its resting contact, and relay 551 to battery. Relay 551, upon energizing, closes a locking circuit for itself including relay 550 and the grounded conductor 524, at armature Relay 550, however, does not energize tor' the time being, owing to the tact that it is short circuited. Stop relay 405, Fig. 6, upon energizing disconnects relay 407 at armature 415, closes a locking circuit for itself at armature 414, and closes the automatic stepping circuit of stepping magnet 403 at armature 413. The wipers 401 and 402 are now advanced in a previously described manner by the buzzer like action of stepping magnet 408 until the wiper 401 becomes into engagement with the last bank contact, which contact is ungrounded. 'Vhen this occurs, the circuit of slow acting relay 406 is opened. Upon deenergizing, after an interval, relay 406 places a shunt around armature 419 and its resting contact at armature 416, and at armature 417 removes direct ground from conductor 425, whereupon relay 550, Fig. 8, being no longer short circuited, energizes in series with relay 551 and removes ground from conductor 169 at armature 557, leaving the said conductor grounded only in the fourth digit set up set- (not shown). As a further result of the energization oi' relay 550, it disconnects conductor 523 trom the third diO'it stop conductor 542 and connects it with conductor 563; and at armature 555 disconnects conductor 525 from relay 551 and connects it to the co responding relay in the fourth digit set up set by way of conductor 584.

Slow acting relay 405, upon deenergizing in response to the opening ot its circuit, which is finally accomplished by the enern gization of relay 550, Fig. S, at armature 555, as described, connects up impulse relay 40'7 again at armature 415, whereupon the counting switch CS begins to operate in the previously described manner, with the result that the impulses oit the fourth digit of the number are sent out at armature 419. in this case the impulses are terminated by wiper 402 coming into engagement with bank contact 446 with which the sixth impulse stop conductor 436-is connected, it being remembered oi course, that the sixth stop conductor 436 is grounded in the fourth digit set up set.

in response to wiper 402 coming into engagement with the grounded contact 446, stop relay 405ijis energized in the usual mannects wiper 349 at armature 273, opens a further point in its own circuit at armature 271i; and at armature 275 places the upper portion of the winding of relay 269 in multiple with the lower portion of the winding. lVhen this occurs, the marginally adjusted relay in the trunk circuit T, Fig. 2, energizes; closes a locking circuit for itself at armature 29, connects trunk conductor 12 through to the lower winding of line relay 7 O at armature 32; thereby completing the following circuit: from ground by way of resistance 8l in the repeater E, resting contact of armature 81 and said armature, lower winding of line relay 70, conductor 65, wiper 62, working contact of armature 32 and said armature, conductor 12, and thence to battery by way of supervisory relay 8 and the lower right hand winding of the associated repeating coil. Supervisory relay 8, however, does not energize over this circuit on account of the high resistance of the resistance coil 8-1 in the repeater E. As a further result of the energization of relay it shifts the circuit of the upper winding of line relay at armature 28 so as to include trunk conductor 10, which conductor is grounded by way of the upper right hand winding of the repeating coil in the 'cord circuit G; opens the circuit of relay 27 at armature 30, whereupon the said relay deenergizes; and at armature 31 opens the circuit of relay 269 of the switch SS. Relay 269, upon deenergizing, opens the circuit of the push button switching relay 251 at armature 278, whereupon the conductors 225 and 226, and 228-233, inclusive, are connected up again to the trunk selecting and sender selecting set shown. As a further result of the deenergization of relay 269, conductor 243 is disconnected from the wiper 302 of the switch TS at armature 279. As astill further result of the deenergization of relay 269, it opens the circuit of the lower winding `of relay 280 at armature 293; and at armature 277 closes a circuit `for switching relay 268 as follows: from ground by way of the normally closed contacts controlled by armature 277, armature 283 and its working contact, switching relay 268, armatures 265 and 266 and their resting contacts, and relay 267 to battery. The closing of this circuit, however, does not perform any useful function at this time and relay 268, which is slightly slow to pull up on account of having a very stiff adjustment, is not able to energize before its circuit is opened at armature 283 'of relay 280, which relay is stiflly adjusted so as to cause it to fall baci; innnediately upon the opening of its circuit. As a further result of the deenergization of relay 280, it opens the circuit of switching` relay 281 at armature 286. Switching relay 281, upon deenergizing, disconnects the wipers Sill-Stil, in-

clusive, thereby finally restoring the condi` tion of the trunk selecting and sender selecting apparatus to normal.

lllhen the called subscriber responds to the ringing of his bell by removing his rcceiver, a direct current bridge is closed across the conductors of his line, whereupon the connector H operates in the well known manner to remove ringing current from the called line and to connect up the back bridge relay 86 with the latter. Bach bridge relay 86, upon energizing over the called line, reverses the incoming trunk conductors as regards their connection with the line relay, whereupon the upper 7inding of electropolarized relay 72 of the repeater E assists tl e lower winding in energizing the relay.

Electropolarized relay 72, upon energizing, disconnects resistance 8lfroni the lower winding of line relay 70 at armature 81, and at armature 8O connects the lower and upper windings of line relay 70 in series and at the saine time disconnects, battery through the resistance 83 from the latter winding. Line relay 70 is now bridged across the conductors 63 and 65 and is accordingly held energized over the established connection in series with the right hand windings of the repeating coil in the cord circ iit 0. lllhen these circuit changes are made, the current flow through the supervisory relay 8 is increased sufficiently to allow it to energize. Upon energizing, supervisory relay 8 places a shunt around the supervisory lamp whereupon the said lamp becomes extinguished, givingl the operator answering supervision. The calling and called subscribers may now converse with each other as desired, the talking circuit being` outlined by the heavy conductors, and after the conversation is finished the two subscribers replace their receivers. lllhen the receiver is replaced at the calling substation il, the circuit of supervisory relay 7 is opened and the said relay, upon ceencn icing, removes the shunt from around supervisory lainp L. whereupon the said lamp becomes lighted.

1When the receiver is replaced at the called substation A, the circuit of back bridge relay 86 is opened, whereupon the said relay deencrgizes, thereby reversing the incomingl trunk conductors back to normal. lVhen this occurs electropolarized relay 7 2 in the repeater E deenergizes, thereby placing battery on the upper nfinding of line relay 70 through the resistance 83 and ground on the lower winding through resistance 84, and separating the two windings. iillhcn this occurs, the supervisory relay 8 iu the cord circuit 0 deenergizes owing to the high resistance 84. in the repeater l, ther-eb;v removing the shunt from around supervisory lamp if, whereupon the said lamp becomes lighted.

'lhe operator upon noting the lighted con- Il il dition ol lalllps L and lf knows thai'l the conve ing and the their receivers, and accordingly she pulls down the connecl n. TWhen the plug,` is ren-loved :iioin the jack I, cut oli;l relay 5 deenergizes, restoring the calling lille to norinal condition, and lililpervisoly laulp L beeonles extinguished.

lllhen the plug l is jack l2 the circuit oil' line relay 70 ot the repeater E and ol sleeve relay :t3 oil the trunk circuit ll are opened. Sleeve relay 2G, upon deellerir'izinilj, opens the circuit of relay at arnflatlu'e Si), llhereupoll the said relay dcenergilies. laine relay ill ot the rellcatcr il, upon deenergizing, opens the circuit oit release relay Tl at arlllatulfe Til, and at arnlatul'e Til opens the bridge across the collductors ol' trunl; line l. llelease relay Tl, upon deenergizing, renlovcs ground troni release trunk conductor lll at aril'lature 78, thereby opening' the circuit et i-lwitcllingl relay 5() oil the line switch (l. whereupon the said relay deencrgiaes.

rllhe autolllatic switches in the distant ef;- cllalflne are released in the well lillown inanner `ill response to the opening' olE the bridge across the conductors oit the 'trunk line l by lille relay l0 ot the repeater E. 'llle entire connection is now released and the apparatus used therein is restored to normal.

Reiter-ring new again to lling 5, a liew points in connection with the apparatus shown there will be considered. llt will be renlelllllered that the operatiY disposes et' the first digit el a desired nunlber by depressing;` one ol the hes 221 or which results ill the operation oli eitherl the switch TS or the switch TS. lt is to be understood that, ill case there are incre than two automatic oilices, as lllally inore 'tl-unir selectiun' switches as needed lll-ly be added and that each will be identical with either the switch TS or the switch Tbl. lt will be urulerstooijl also that a push button silnilar to push button 221 or will be added for each oil ille added trulli: selecting),l switches. tlbviously the saine addition in trunk selectilu;A switches illust be iliade in the reserve set to which the conductors QQJJGQ, incliiisive, extend.

Referring` now to the release push button Bla, its function will be explained. It seinetilnes occurs that an operator, in setting up a nulnber, realises that she has operated the wrongn button in which case she will desire to release the part ot the nulllber that is stored up and start over again. This she accomplishes by operating' the push button 215 which places ground upon conductor 233, thereby closing' the following circuit ilior release relay 4108., Figi. (l: lil'onlY ground by way ot conductor 23?. arlnaturc 235 and its resting contact, conductor 248, wiper llled subscribers have replaced "enloved troni the itioll colllpleted and that the call' and the contact with which it is ill eng nient, conductor 151, armature 108 and its resting contact, conductor 166, and release relay flOS to battery. Release relay lull, upon energizing', removes ground from colllliciol- 42d at armature 4:20, whereilpl'lil relay 4352, which has been energized by a previous operation in series with one of the other relays, relay -T-l for example, deenergizes, thereby reulovillgv lground troni conductor .at arn'lature 481, whereupon the corresponding relay in the next storage set, Fig. 8, (ficelle:v gizes in case it has been operated. ssuin ing that relay fli4l was energized in seriesy with relay 452 the latter relay also deenergized when ground was removed Yiiron'l conductor 12st, thereby disconnecting' the lirst digit stop conductor lil trein the tolli-th inlpulse stop conductor 4,34. When the operator releases the release push button, ground is replaced on conductor 124-, lllhereupoll relays L153 and 45st enere'ize and connect ull conductors 141-150, inclusive, with relays 47h48@ inclusive, respectively.

In connection with the reserve set, to which the conductors 2525262, inclusive, Fig. 5, extend, it may be pointed out that switching' relay 251, upon energizing in response to the closure of its circuit by relay 269. when the operator plugs in, after having up a number, switches the set ot push buttons over to the reserve set. llt the reserve set is not used after this tilne and betere relay 269 deenergizes, after the sending' out of the last digit in the desired nulllber, relay 251 deenergizes and connects the set oi push buttons to the set shown. However. il the operator gets a second call immediately alter having set up the lirst one and in that case opera-tes one oit the push buttons 221 or while switching` relay 251 is energized, conductor 262 beconies grounded in the reserve set at an armature correspondingl to armature 28S ot relay Q80, when the associated relay energizes in response to the manipulation oi one of the said push buttons 252i or 29,2, it beingl remembered of course, that colln ductor E262 extends to a pair oit normally closed contacts in the reserve set instead oit a pair ot norlnally open contacts such as are controlled by armature 278 ol relay Q69. Obviously.` in this case relay 251 is held energized until the relay corresponding' to relay 269 in the reserve set energizes alter the last digit, ill the nulnber set up, is sent out.

It will be observed that the wipers 343- 348. inclusive, ol the switch SS are norinally connected to the push buttons 201-Q10, inelusive, and 215. This however, does not cause any harin to result for the reason that the operator will not manipulate any ot these buttons except in the regular course ot setting' up a connection. However. it she should accidentally operate one ot these buttons no harin would result because they are fl (l disconnected at armatures 252 and 253 of relay 268. Of course it is possible that an operator could maliciously interfere with the setting up of a call by another operator by purposely operating two buttons simultaneously, 201 and 203 for example, which would result in connecting conductors 228 and 229 together. This, however, is'a very remote possibility. It is obvious that, in case it is deemed advisable in special cases, the conductors leading to the wipers 343-348, inclusive, may be carried through normally open contacts on relay 268 in the same manner as conductor 249, which is connected with wiper 34:9.

In Fig. l, the jacks J and J which are inultipled with the jacks J and J 2, respectively, are assumed to be at another operators position. The lamp at the jack J, however, is notmultipled with the lamp LAVL at the jack J 2, but is connected by way of a conductor, corresponding to conductor 305, to the bank of the trunk selecting` switch at that position corresponding to the trunk se lecting switch TS, Fig. 5. These two lamps are connected on separate circuits in order to prevent confusion which would result if they should both light when it is desired to make an indication to an operator at one position only.

Referring now to the marginally adjusted relay 27 in the trunk circuit T, Fig. 2, the function of this relay will be explained. Tt will be remembered that when sleeve relay 26 energizes in response to the operator plugging in after having set up a number, in addition to causing the sender to begin to send out the impulses to operate the automatic switches, the said relay 26 closes a circuit for the upper winding of relay 27 at armature 34, whereupon the said relay 27 energizes just sufficiently to operate armature 37, thereby closing a locking circuit for itself through its lower winding. The lower winding, however, is ineffective for the time being owing to the' fact that it is short circuited. In the usual course of operation the sending is uninterrupted and when relay energizes after the last digit is sent out the circuit of the upper winding of relay 27 is opened at armature 30 and the said relay deenergizes. However, it may occur that the operator will pull the plug P from the j ack J2 before the sending is completed. This may result from the hanging up of the calling subscriber, for example.

TWithout relay 27, in case the operator does pull the plug before the number is coinpletely sent out, the sender is stopped before the sending is completed and a lock up of various relays occurs and the sender is disabled until an attendant clears the trouble. With relay 27 in the circuit, as shown, however, the sender continues to function until the last digit set up is sent out, as will now be explained. Assuming now that the operator pulls the plug P from the jack J2 before the sender has sent the last digit of the number and consequently before relay 25 has energized. Sleeve relay 26, upon deenergizing, opens the initial circuit of the upper winding of' relay 27 at armature 34, thereby removing the short circuit from the eliiciently wound lower winding of the said relay 27. lVhen this occurs, the said relay 27 pulls all the way up; places a shunt around armature and its working contact, of relay 26, at armature 38, and at armature 36 opens the circuit of the upper winding of line relay of the repeater E, whereupon the partly established connection is released.

Armature 85 and its working contact having been bridged, the sender continues to send out the remaining digit in the desired number in the usual manner, but, owing to the operation of relay 27, no result is produced in the automatic switches, and when the last digit has been sent out, relay 2: first pulls all the way up in the usual manner, and then, since sleeve relay 26 is deenergized, the said relay 25 deenergizes because no locking circuit is closed for it.

The various features of the invention having been described and ascertained in the foregoing will now be pointed out in the appended claims.

That is claimed is:

l. In a telephone system, automatic switches, an operators position, trunks extending from said position to said switches, a plurality of senders for controlling said switches, a set of number registering push buttons for controlling said senders, a pair of automatic selecting switches individual to said position, and means controlled by the operator for causing one of said selecting switches to select one of said trunks and the other to select one of said senders.

2. Tn a telephone system, automatic switches, an operators position, a plurality of groups of trunks extending therefrom to said switches, a plurality of operators senders for controlling said switches, a set of number registering push buttons, another set of push buttons comprising a push button for each of said groups of trunks, asender selecting switch associated with said groups of push buttons, a plurality of trunk selecting switches associated with said groups of push buttons, one trunk selecting switch for each of said groups of trunks and corresponding thereto, and means controlled by the operation of one of said push buttons in the second mentioned group for causing the trunk selecting switch associated therewith to select an idle trunk in the associated group and for causing said sender selecting switch to select an idle sender.y

3. In a telephone system, an automatic switch, an operators position, a calling line llt) 

